1. Field of the Invention
The present invention relates generally to a socket assembly and more particularly to an assembly for removably coupling an electronic component to conductive paths on a printed wiring board.
2. Description of the Related Art
High speed logic circuits contained in integrated circuit semiconductor chips typically require at least one DC supply voltage at various circuit locations. In telecommunication systems, bridge rectifiers are commonly used to provide the required DC supply voltages and/or to protect electronic circuits from voltages of reverse polarity. In the U.S., positive 24 volts are normally used to power the telecommunications equipment. Foreign telecommunication equipment operates according to a different standard and is normally powered by negative 48 volts. These supply voltages are presently provided by means of a bridge rectifier typically contained in a separate module that is mounted at a location remote from the printed wiring board on which the logic circuits are located. The DC current provided by the bridge rectifier is typically conductively coupled to the printed wiring board by means of a wire harness which couples the bridge rectifier to the printed wiring board. The wire harness can be three feet or more in length. On the printed wiring board the current flows through thin-film conductive paths to integrated telecommunication circuit packages. All of the power to the telecommunications circuits on the printed wiring board passes through the bridge rectifier. Currently, for various reasons, bridge rectifiers that are mounted on printed wiring boards are normally limited to operate at a current of only 1 amp or less.
Industry standard high power 20 and 35 amp bridge rectifiers are not currently mounted on the surface of a printed wiring board. Some of the reasons for this are:
1. The use of Faston or wire wrap terminals are labor intensive and required the use of costly pigtail attachments to the printed wiring board; and
2. Printed wiring boards that have through hole solderable connections do not support conduction cooled applications which is the normal method of cooling a bridge rectifier.
The present day method of electrically coupling a bridge rectifier to integrated chips on a printed wiring board is by mounting the bridge rectifier to a heat conducting plate which may be located three or more feet from the printed wiring board and connecting the bridge rectifier to the printed wiring board with wire conductors. The use of wire conductors creates difficulties in maintaining a constant and regulated DC supply voltage at the integrated circuit chips. One such difficulty results from variations in the voltage drop in the wire leads between the bridge rectifier and the contacts of the integrated chips. As the length of the wire leads increases, the resistance of the leads increases. Additionally, as the complexity of the circuits in an integrated circuit chip increases, which normally causes a corresponding increase in the amount of current demanded by the integrated circuit chips, variations in the current demand during normal operation of the integrated circuit chip results in variations in the voltage drop across the power supply lines. Normally, the voltage drop along the supply lines can be reduced by increasing the cross sectional area of the conductors as much as possible. Unfortunately, when current demand is high and the constraints on the printed wiring board space is significant, then a designer may not be able to increase the size of the metal conductive paths enough to provide DC supply voltages which are adequate to guarantee proper operation of integrated circuits that have high transient or continuous loading characteristics.
Another drawback with the bridge rectifier not being located on the printed wiring board is the time it takes for the power supply to sense a change in current demand of the integrated circuits. Shorter path lengths between the integrated circuits and the DC power supply allows for more rapid correction of the output voltages generated by the power supply when the level of the output voltage is either above or below a specified value.
There is an unfulfilled need for a structure which can be used to mount a high power bridge rectifier quickly and economically onto the surface of a printed wiring board.
The problem of locating a bridge rectifier on a printed wiring board and doing so economically is solved and a technical advance achieved by an assembly comprised of a first member mounted directly on the printed wiring board and a second member which connects a bridge rectifier to the first member. The first member has a first set of discrete contacts adapted to be soldered to conductive paths on the printed wiring board and a second set of contacts each coupled to one of the first set of contacts. The first member supports an opening that extends therethrough and is sized to accept a bridge rectifier. The second member supports a third set of contacts which are adapted to engage the second set of contacts and a fourth set of contacts each one of which is electrically coupled to one of the third set of contacts. The fourth set of contacts are spaced to engage the contacts of a bridge rectifier and are located to position the bridge rectifier within the opening of the first member, or are located to position the bridge rectifier beyond the opening of the first member. In addition, the fourth set of contacts can be two sets of contacts for positioning the bridge rectifier on either side of the second member.